Mechanism of Co–C photodissociation in adenosylcobalamin
| Autor: | Maria Jaworska, Piotr Lodowski, Brady D. Garabato, Pawel M. Kozlowski |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Ligand field theory
General Physics and Astronomy Ligands 010402 general chemistry 01 natural sciences Molecular physics Organometallic Compounds medicine Singlet state Physical and Theoretical Chemistry Group 2 organometallic chemistry 010405 organic chemistry Chemistry Photodissociation Cobalt Adenosylcobalamin 0104 chemical sciences Vitamin B 12 Metals Excited state Potential energy surface Quantum Theory Density functional theory Cobamides Atomic physics medicine.drug |
| Zdroj: | Physical Chemistry Chemical Physics. 18:19070-19082 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/c6cp02136k |
| Popis: | A mechanism of Co-C bond photodissociation in the base-on form of adenosylcobalamin (AdoCbl) was investigated by time-dependent density functional theory (TD-DFT). The key mechanistic step involves singlet radical pair (RP) generation from the first electronically excited state (S1). To connect TD-DFT calculations with ultra-fast excited state dynamics, the potential energy surface (PES) of the S1 state was constructed using Co-C and Co-NIm axial coordinates. The S1 PES can be characterized by two minima separated by a seam resulting from the crossing of two surfaces, of metal-to-ligand charge transfer (MLCT) character near the minimum, and a shallow ligand field (LF) surface at elongated axial bond distances. Only one possible pathway for photolysis (path A) was identified based on energetic grounds. This pathway is characterized by the first elongation of the Co-C bond, followed by photolysis from an LF state where the axial base is partially detached. A new perspective on the photolysis of AdoCbl is then gained by connecting TD-DFT results with available experimental observations. |
| Databáze: | OpenAIRE |
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